Naphtyl ring

Pd(II) complexes with enantiomerically pure orthometallated benzylamines have been studied in detail because they are used for the resolution of chiral ligands. For dimethyl(l-(a-naphtyl)-ethyl)amine it is clear that the chelate prefers the conformation with the benzylic Me in axial position, thus avoiding interactions with the naphtyl ring. This leads to a 8 conformation for the R amine (Figure 4.6), and to a X conformation for the Samine [23-26]. 

R= Ph, 4-Me-Ph, 4-CI-Ph, Naphtyl, 3-MeO-Ph, 4-F-Ph Scheme 5.45 NHC-Pd catalysed ring closure of o-bromobenzyl ketones... 

Formation of the second aromatic ring in naphtalene is thought to occur by two subsequent additions of acetylene to a phenyl radical (CgHs) or directly by recombination of two cyclopentadienyl (C5H5) radicals, in both cases followed by hydrogen elimination. A three-ring compound can be formed in a similar way, by subsequent additions of acetylene to the naphtyl radical, or by an indenyl radical reacting with the cyclopentadienyl radical. 

The [4 + 2] photooxygenation of dienes and benzene rings leads to endo oxides. With chiral naphtyl alcohols 191,192, and 193 were formed with a dias reomeric excess up to 90%, when the reaction was carried out at — 30°C in CD (Scheme 50). In order to explain the selectivity in aprotic solvents, it was propo that an intramolecular hydrogen bond can be developed between the hydrox group and 102 during the approach of the dienophile from one or the other si of the naphthalene ring, favoring one of the two diastereoisomeric transit states. 

Molecular superimposition is the most critical step in any CoMFA study and it was therefore thoroughly studied by testing several different alignments. Benazoline was chosen as the template, since it is the most active ligand and has a relatively limited conformational mobility. Its lowest minimum energy conformer, in which the inter-ring torsion angle between naphtyl and imidazoline moieties is -32.3, was selected for the different molecular overlays. 

The substitution of alkyle or naphtyle groups, either on the benzene ring or on the nitrogen atom, allows for another colour succession [32,33] for instance, poly N-naphthylaniline leads, with increasing potential, to the succession of yellow, red, purple and dark blue colours. 

---